The present disclosure relates generally to printed circuit boards, and, more particularly, to the expansion and contraction of conductive polymers within drilled holes of printed circuit boards.
Often multiple vias are used in a multi-layered printed circuit board to electrically connect annular contact pads of conductive traces in differing (conductive) layers of the board. During the manufacturing of the printed circuit board, the vias may be created by plating drilled holes in the board with a conductive material (typically copper). The entire depth of the via, including an unused portion of the via called a stub, is generally plated with the copper material. Left unchanged, the plated stub portion may adversely degrade electrical signals traveling through the desired portion of the via (i.e., into a contact pad of a desired trace escape layer) during use of the completed circuit board. In order to reduce the impact of stubs on circuit board performance, the stubs may be removed from the board, or at least shortened, during the manufacturing process by means such as backdrilling.